Surface Expression Research Articles

Profiles of teachers' emotional labour during COVID-19 and the consequences on mental health: A comparison between online and offline teaching.

Despite increasing attention on emotional labor in teacher well-being research, person-centered studies are relatively scarce, particularly concerning the emotional labor of online teaching during COVID-19 and its effects on teachers' non-work-related mental health. This study aims to address these gaps by examining emotional labor profiles and their consequences on job satisfaction, depression, and anxiety among Chinese teachers involved in either online or offline teaching during October-December 2022. Two samples of teachers were analyzed altogether: one engaged in online teaching (N=605) and the other in offline teaching (N=394). Latent profile analysis was used to identify emotional labor profiles based on three strategies: surface acting, deep acting, and expression of naturally felt emotions. A total of four subgroups of emotional workers were identified: natural expressors, actors, flexible regulators, and authentic regulators. Significant differences were found between online and offline teaching, with a higher proportion of actors and fewer flexible regulators in the online condition, suggesting that the screen acts as a barrier to authentic emotional display. Among the four classes, actors scored lowest on job satisfaction and highest on depression and anxiety, whereas authentic regulators were the most adaptive, especially in online settings. The findings highlight the impact of online teaching on teachers' emotional labor profiles and mental health, with practical implications for optimizing online teaching environments and supporting teacher well-being.

Postsynaptic Density Proteins and Their Role in the Trafficking of Group I Metabotropic Glutamate Receptors.

Glutamate is the major excitatory neurotransmitter in the mammalian central nervous system that regulates multiple different forms of synaptic plasticity, including learning and memory. Glutamate transduces its signal by activating ionotropic glutamate receptors and metabotropic glutamate receptors (mGluRs). Group I mGluRs belong to the G protein-coupled receptor (GPCR) family. Regulation of cell surface expression and trafficking of the glutamate receptors represents an important mechanism that assures proper transmission of information at the synapses. There is growing evidence implicating dysregulated glutamate receptor trafficking in the pathophysiology of several neuropsychiatric disorders. The postsynaptic density (PSD) region consists of many specialized proteins which are assembled beneath the postsynaptic membrane of dendritic spines. Many of these proteins interact with group I mGluRs and have essential roles in group I mGluR-mediated synaptic function and plasticity. This review provides up-to-date information on the molecular determinants regulating cell surface expression and trafficking of group I mGluRs and discusses the role of few of these PSD proteins in these processes. As substantial evidences link mGluR dysfunction and maladaptive functioning of many PSD proteins to the pathophysiology of various neuropsychiatric disorders, understanding the role of the PSD proteins in group I mGluR trafficking may provide opportunities for the development of novel therapeutics in multiple neuropsychiatric disorders.

7640 The first description of an MC4R variant in a patient with Kallmann syndrome and obesity

Abstract Disclosure: A.A. Aslam: None. S. Lim: None. R. Willemsen: None. K. Koysombat: None. M. Young: None. W.S. Dhillo: None. A. Abbara: None. S. Howard: None. E.F. Gevers: None. Introduction: Pathogenic MC4R gene variants result in hyperphagia and early onset obesity but puberty is not usually affected. We describe an MC4R variant in a patient with Kallmann syndrome and obesity. A 16 year old male with repaired Tetralogy of Fallot, anosmia, autism and anxiety, was referred with obesity and delayed puberty. His birth weight was 3360 g (-0.26 SDS). Height was -1.31 SDS, BMI 30.7 kg/m2. He had high arched palate, normal skin and hair colour, mild hypertelorism and upward slanting palpebral fissures. Pubertal staging was A2P1G1 5ml testes bilaterally. Results: LHRH test showed borderline low peaks (LH 5.0 U/L, FSH 2.6 U/L) and inhibin B 108 pg/mL (25-325 pg/mL). MRI brain showed hypoplastic olfactory bulbs, absent olfactory sulci and normal pituitary anatomy. CGH microarray, karyotype and the UK hypogonadism gene panel were normal. He underwent whole genome sequencing in the Genetic Factors Affecting the Timing of Puberty Study; no abnormalities in 52 known genes associated with GnRH deficiency were found but a previously described heterozygous variant was detected, MC4R c.542G>A, p.Gly181Asp, classified pathogenic and absent in control databases. Management: He was commenced on Testosterone but showed progression of testicular size to 10 mL and testosterone was stopped but required restarting. Repeat investigations off treatment, aged 22 years (height 178 cm, BMI 42 kg/m2, testes 15 mL): inhibin B 66 pg/mL, testosterone 2 nmol/L, baseline LH 2.4 U/L, stimulated peak 24.9 U/L, baseline FSH 1.2 U/L, stimulated peak 4.2 U/L. Cortisol and IGF1 were in the normal range. He also developed autoimmune hypothyroidism with raised TPO antibodies (TSH 24.7 mU/L, FT4 5.6 pmol/L). Discussion: Previous in vitro work has shown complete loss of function of MC4R p.Gly181Asp due to reduced cell surface expression and reduced binding to a-MSH. Heterozygous p.Gly181Asp variants have been described in several children/adults with obesity; but hypogonadism in heterozygous carriers has not. Homozygous MC4R p.Gly181Asp was found in a male with obesity and partial HH thought to be due to abnormal GnRH production but with normal olfactory bulbs. We are the first to describe a heterozygous MC4R p.Gly181Asp variant in a patient with partial hypogonadism and anosmia with hypoplastic bulbs in addition to obesity. Interaction between POMC-MC-leptin circuits and Kisspeptin-GnRH circuits is recognised although not completely understood. Previous work has shown that a subset of kisspeptin neurons express MC4R and that KNDy neurones receive synaptic input from POMC neurons. In addition, inhibition of MC4R/MC3R results in delayed onset of puberty in rats. Our results support a role for MC4R in GnRH secretion and potentially olfactory /GnRH neuronal migration. Assessment of spontaneous gonadotrophin production and response of gonadotrophin production to kisspeptin stimulation is currently in progress. Presentation: 6/1/2024

9293 Do Obesity-Associated MRAP2 Variants Modulate MC4R and GHSR Signaling?

Abstract Disclosure: A.V. Rodriguez Rondon: None. F. Volker: None. M.S. Welling: None. C. de Groot: None. M.M. van Haelst: None. E.L. van den Akker: None. E.F. van Rossum: None. P.J. Delhanty: None. J.A. Visser: None. Melanocortin 2 receptor accessory protein 2 (MRAP2) is a membrane-bound protein expressed on hypothalamic neurons that modulate the function of appetite-regulating receptors, including melanocortin-4 receptor (MC4R) and growth hormone secretagogue receptor (GHSR). While pathogenic variants in the MRAP2 gene are associated with obesity, the mechanism for this remains unclear. The aim of this study is to investigate the functional impact of wildtype (WT) MRAP2 and MRAP2 variants on MC4R and GHSR signaling. Four MRAP2 variants (S80F, R125C, P167A and Q174X) were identified in patients with obesity by obesity gene panel analysis. The functional effects of these variants were analyzed by co-transfecting HEK293 cells with expression plasmids encoding WT or variant MRAP2 and WT MC4R or WT GHSR. Endpoint analyses included cell surface expression, and ligand-induced second messenger responses (α-MSH-induced cAMP response for MC4R and ghrelin-induced Ca2+ mobilization for GHSR), β-arrestin-2 recruitment, and internalization. WT MRAP2 significantly decreased basal MC4R cell surface expression by 68.1±4.3% (p<0.001). In the absence of MRAP2, α-MSH induced MC4R internalization. However, in the presence of WT MRAP2, MC4R cell surface expression was increased by 89.4±6.9% upon α-MSH stimulation (p<0.001). GHSR cell surface expression and ghrelin-induced internalization were not affected by WT MRAP2. Furthermore, in the cells expressing MC4R with WT MRAP2, the maximal α-MSH-induced cAMP and β-arrestin-2 recruitment responses were increased by 29.8±5.2% and 81.3±4.2% respectively (p<0.001), compared with those lacking MRAP2. We also investigated GHSR ghrelin-induced Ca2+ mobilization and found that, in the presence of WT MRAP2, this increased significantly by 95.37±21.9%, (p<0.0003). However, ghrelin-induced β-arrestin-2 recruitment was suppressed by 69.8±7.6%, (p<0.001). Using these endpoints we found no effect of the variants on the ability of MRAP2 to modulate ligand-induced signaling by MC4R and GHSR. Our results indicate that WT MRAP2 enhances the cAMP response by increasing MC4R cell membrane expression upon α-MSH stimulation, and enhances GHSR Ca2+ mobilization by decreasing β-arrestin-2 recruitment upon ghrelin stimulation. The MRAP2 variants assessed in this study behaved as WT MRAP2 in α-MSH-induced MC4R and ghrelin-induced GHSR signaling, suggesting that these may be benign variants. However, since MRAP2 can modulate multiple receptors, we cannot rule out that these MRAP2 variants affect other appetite-regulating receptors and thereby influence body weight regulation via other pathways. Presentation: 6/3/2024

7908 GPNMB Promotes Tumor Growth And Is A Biomarker For Lymphangioleiomyomatosis (LAM)

Abstract Disclosure: E. Gibbons: None. M. Taya: None. H. Wu: None. S. Lopa: None. J. Moss: None. E.P. Henske: None. F.X. McCormack: None. S.R. Hammes: None. Lymphangioleiomyomatosis (LAM) is a rare, progressive cystic lung disease affecting almost exclusively female-sexed individuals. The cysts represent regions of lung destruction caused by smooth muscle tumors containing mutations in one of the two tuberous sclerosis (TSC) genes. mTORC1 inhibition slows but does not stop LAM advancement. Furthermore, monitoring disease progression is hindered by insufficient biomarkers. Therefore, new treatment options and biomarkers are needed. LAM cells express melanocytic markers, including Glycoprotein Non-Metastatic Melanoma Protein B (GPNMB). The function of GPNMB in LAM is currently unknown; however, GPNMB’s unique cell surface expression on tumor versus benign cells makes GPNMB a potential therapeutic target, and persistent release of its extracellular ectodomain suggests potential as a serum biomarker. Here we establish that GPNMB regulates TSC2-null tumor cell invasion as well as TSC2-null xenograft tumor growth, and that GPNMB expression is dependent on mTORC1 signaling. Further, we show that GPNMB’s ectodomain is released from the cell surface of TSC2-null cells by ADAM10 and 17 proteases, and we identify the protease target sequence on GPNMB. In fact, mutating this cleavage sequence so that the GPNMB ectodomain can no longer be shed results in cessation of TSC2-null tumor growth. Finally, we demonstrate that GPNMB’s ectodomain is present at higher levels in LAM patient serum compared to healthy controls, and that ectodomain levels decrease with mTORC1 inhibition, making it a potential LAM biomarker. Presentation: 6/3/2024

7908 GPNMB Promotes Tumor Growth and is a Biomarker for Lymphangioleiomyomatosis (LAM)

Abstract Disclosure: E. Gibbons: None. M. Taya: None. H. Wu: None. S. Lopa: None. J. Moss: None. E.P. Henske: None. F.X. McCormack: None. S.R. Hammes: None. Lymphangioleiomyomatosis (LAM) is a rare, progressive cystic lung disease affecting almost exclusively female-sexed individuals. The cysts represent regions of lung destruction caused by smooth muscle tumors containing mutations in one of the two tuberous sclerosis (TSC) genes. mTORC1 inhibition slows but does not stop LAM advancement. Furthermore, monitoring disease progression is hindered by insufficient biomarkers. Therefore, new treatment options and biomarkers are needed. LAM cells express melanocytic markers, including Glycoprotein Non-Metastatic Melanoma Protein B (GPNMB). The function of GPNMB in LAM is currently unknown; however, GPNMB’s unique cell surface expression on tumor versus benign cells makes GPNMB a potential therapeutic target, and persistent release of its extracellular ectodomain suggests potential as a serum biomarker. Here we establish that GPNMB regulates TSC2-null tumor cell invasion as well as TSC2-null xenograft tumor growth, and that GPNMB expression is dependent on mTORC1 signaling. Further, we show that GPNMB’s ectodomain is released from the cell surface of TSC2-null cells by ADAM10 and 17 proteases, and we identify the protease target sequence on GPNMB. In fact, mutating this cleavage sequence so that the GPNMB ectodomain can no longer be shed results in cessation of TSC2-null tumor growth. Finally, we demonstrate that GPNMB’s ectodomain is present at higher levels in LAM patient serum compared to healthy controls, and that ectodomain levels decrease with mTORC1 inhibition, making it a potential LAM biomarker. Presentation: 6/3/2024

9308 GPNMB Promotes Tumor Growth And Is A Biomarker For Lymphangioleiomyomatosis (LAM)

Abstract Disclosure: E. Gibbons: None. M. Taya: None. H. Wu: None. S. Lopa: None. J. Moss: None. E.P. Henske: None. F.X. McCormack: None. S.R. Hammes: None. Lymphangioleiomyomatosis (LAM) is a rare, progressive cystic lung disease affecting almost exclusively female-sexed individuals. The cysts represent regions of lung destruction caused by smooth muscle tumors containing mutations in one of the two tuberous sclerosis (TSC) genes. mTORC1 inhibition slows but does not stop LAM advancement. Furthermore, monitoring disease progression is hindered by insufficient biomarkers. Therefore, new treatment options and biomarkers are needed. LAM cells express melanocytic markers, including Glycoprotein Non-Metastatic Melanoma Protein B (GPNMB). The function of GPNMB in LAM is currently unknown; however, GPNMB’s unique cell surface expression on tumor versus benign cells makes GPNMB a potential therapeutic target, and persistent release of its extracellular ectodomain suggests potential as a serum biomarker. Here we establish that GPNMB regulates TSC2-null tumor cell invasion as well as TSC2-null xenograft tumor growth, and that GPNMB expression is dependent on mTORC1 signaling. Further, we show that GPNMB’s ectodomain is released from the cell surface of TSC2-null cells by ADAM10 and 17 proteases, and we identify the protease target sequence on GPNMB. In fact, mutating this cleavage sequence so that the GPNMB ectodomain can no longer be shed results in cessation of TSC2-null tumor growth. Finally, we demonstrate that GPNMB’s ectodomain is present at higher levels in LAM patient serum compared to healthy controls, and that ectodomain levels decrease with mTORC1 inhibition, making it a potential LAM biomarker. Presentation: 6/3/2024

6789 Do Obesity-Associated MRAP2 Variants Modulate MC4R and GHSR Signaling?

Abstract Disclosure: A.V. Rodriguez Rondon: None. F. Volker: None. M.S. Welling: None. C. de Groot: None. M.M. van Haelst: None. E.L. van den Akker: None. E.F. van Rossum: None. P.J. Delhanty: None. J.A. Visser: None. Melanocortin 2 receptor accessory protein 2 (MRAP2) is a membrane-bound protein expressed on hypothalamic neurons that modulate the function of appetite-regulating receptors, including melanocortin-4 receptor (MC4R) and growth hormone secretagogue receptor (GHSR). While pathogenic variants in the MRAP2 gene are associated with obesity, the mechanism for this remains unclear. The aim of this study is to investigate the functional impact of wildtype (WT) MRAP2 and MRAP2 variants on MC4R and GHSR signaling. Four MRAP2 variants (S80F, R125C, P167A and Q174X) were identified in patients with obesity by obesity gene panel analysis. The functional effects of these variants were analyzed by co-transfecting HEK293 cells with expression plasmids encoding WT or variant MRAP2 and WT MC4R or WT GHSR. Endpoint analyses included cell surface expression, and ligand-induced second messenger responses (α-MSH-induced cAMP response for MC4R and ghrelin-induced Ca2+ mobilization for GHSR), β-arrestin-2 recruitment, and internalization. WT MRAP2 significantly decreased basal MC4R cell surface expression by 68.1±4.3% (p<0.001). In the absence of MRAP2, α-MSH induced MC4R internalization. However, in the presence of WT MRAP2, MC4R cell surface expression was increased by 89.4±6.9% upon α-MSH stimulation (p<0.001). GHSR cell surface expression and ghrelin-induced internalization were not affected by WT MRAP2. Furthermore, in the cells expressing MC4R with WT MRAP2, the maximal α-MSH-induced cAMP and β-arrestin-2 recruitment responses were increased by 29.8±5.2% and 81.3±4.2% respectively (p<0.001), compared with those lacking MRAP2. We also investigated GHSR ghrelin-induced Ca2+ mobilization and found that, in the presence of WT MRAP2, this increased significantly by 95.37±21.9%, (p<0.0003). However, ghrelin-induced β-arrestin-2 recruitment was suppressed by 69.8±7.6%, (p<0.001). Using these endpoints we found no effect of the variants on the ability of MRAP2 to modulate ligand-induced signaling by MC4R and GHSR. Our results indicate that WT MRAP2 enhances the cAMP response by increasing MC4R cell membrane expression upon α-MSH stimulation, and enhances GHSR Ca2+ mobilization by decreasing β-arrestin-2 recruitment upon ghrelin stimulation. The MRAP2 variants assessed in this study behaved as WT MRAP2 in α-MSH-induced MC4R and ghrelin-induced GHSR signaling, suggesting that these may be benign variants. However, since MRAP2 can modulate multiple receptors, we cannot rule out that these MRAP2 variants affect other appetite-regulating receptors and thereby influence body weight regulation via other pathways. Presentation: 6/3/2024

NAT10/ac4C/JunB facilitates TNBC malignant progression and immunosuppression by driving glycolysis addiction

BackgroundN4-Acetylcytidine (ac4C), a highly conserved post-transcriptional mechanism, plays a pivotal role in RNA modification and tumor progression. However, the molecular mechanism by which ac4C modification mediates tumor immunosuppression remains elusive in triple-negative breast cancer (TNBC).MethodsNAT10 expression was analyzed in TNBC samples in the level of mRNA and protein, and compared with the corresponding normal tissues. ac4C modification levels also measured in the TNBC samples. The effects of NAT10 on immune microenvironment and tumor metabolism were investigated. NAT10-mediated ac4C and its downstream regulatory mechanisms were determined in vitro and in vivo. The combination therapy of targeting NAT10 in TNBC was further explored.ResultsThe results revealed that the loss of NAT10 inhibited TNBC development and promoted T cell activation. Mechanistically, NAT10 upregulated JunB expression by increasing ac4C modification levels on its mRNA. Moreover, JunB further up-regulated LDHA expression and facilitated glycolysis. By deeply digging, remodelin, a NAT10 inhibitor, elevated the surface expression of CTLA-4 on T cells. The combination of remodelin and CTLA-4 mAb can further activate T cells and inhibite tumor progression.ConclusionTaken together, our study demonstrated that the NAT10-ac4C-JunB-LDHA pathway increases glycolysis levels and creates an immunosuppressive tumor microenvironment (TME). Consequently, targeting this pathway may assist in the identification of novel therapeutic strategies to improve the efficacy of cancer immunotherapy.

Extracellular bimolecular fluorescence complementation for investigating membrane protein dimerization: a proof of concept using class B GPCRs.

Bimolecular fluorescence complementation (BiFC) methodology uses split fluorescent proteins to detect interactions between proteins in living cells. To date, BiFC has been used to investigate receptor dimerization by splitting the fluorescent protein between the intracellular portions of different receptor components. We reasoned that attaching these split proteins to the extracellular N-terminus instead may improve the flexibility of this methodology and reduce the likelihood of impaired intracellular signal transduction. As a proof-of-concept we used receptors for calcitonin gene-related peptide, which comprise heterodimers of either the calcitonin or calcitonin receptor-like receptor in complex with an accessory protein (receptor activity-modifying protein 1). We created fusion constructs in which split mVenus fragments were attached to either the C-termini or N-termini of receptor subunits. The resulting constructs were transfected into Cos7 and HEK293S cells, where we measured cAMP production in response to ligand stimulation, cell surface expression of receptor complexes, and BiFC fluorescence. Additionally, we investigated ligand-dependent internalization in HEK293S cells. We found N-terminal fusions were better tolerated with regards to cAMP signaling and receptor internalization. N-terminal fusions also allowed reconstitution of functional fluorescent mVenus proteins, however fluorescence yields were lower than with C-terminal fusion. Our results suggest that BiFC methodologies can be applied to the receptor N-terminus, thereby increasing the flexibility of this approach, and enabling further insights into receptor dimerization.

Design of a Robust Flow Cytometric Approach for Phenotypical and Functional Analysis of Human Monocyte Subsets in Health and Disease.

Human monocytes can be subdivided into phenotypically and functionally different classical, intermediate and non-classical monocytes according to the cell surface expression of CD14 and CD16. A precise identification and characterisation of monocyte subsets is necessary to unravel their role in inflammatory diseases. Here, we compared three different flow cytometric strategies (A-C) and found that strategy C, which included staining against CD11b, HLA-DR, CD14 and CD16, followed by several gating steps, most reliably identified monocyte subtypes in blood samples from healthy volunteers and from patients with stable coronary heart disease (CHD) or ST-elevation myocardial infarction (STEMI). Additionally, we established a fixation and permeabilisation protocol to enable the analysis of intracellular markers. We investigated the phagocytosis of lipid nanoparticles, the uptake of 2-NBD-glucose and the intracellular levels of CD74 and HLA-DM. This revealed that classical and intermediate monocytes from patients with STEMI showed the highest uptake of 2-NBD-glucose, whereas classical and intermediate monocytes from patients with CHD took up the largest amounts of lipid nanoparticles. Interestingly, intermediate monocytes had the highest expression level of HLA-DM. Taken together, we present a robust flow cytometric approach for the identification and functional characterisation of monocyte subtypes in healthy humans and patients with diseases.

Molecular Phenotypes Segregate Missense Mutations in SLC13A5 Epilepsy

The sodium-coupled citrate transporter (NaCT, SLC13A5) mediates citrate uptake across the plasma membrane via an inward Na+ gradient. Mutations in SLC13A5 cause early infantile epileptic encephalopathy type-25 (EIEE25, SLC13A5 Epilepsy) due to impaired citrate uptake in neurons and astrocytes. Despite clinical identification of disease-causing mutations, underlying mechanisms and cures remain elusive. Here we mechanistically classify six frequent SLC13A5 mutations by phenotyping their protein cell surface expression and citrate transport functions. Mutants C50R, T142M, and T227M exhibit impaired citrate transport despite normal expression at the cell surface. In contrast, mutations G219R, S427L, and L488P show low total protein expression levels, absence of mature, glycosylated proteins at the cell surface, retention of the proteins in the endoplasmic reticulum, and diminished transport activity. This mechanistic classification divides SLC13A5 mutants into two groups, Class I (C50R, T142M, and T227M) and Class II (G219R, S427L, and L488P). Importantly, mutants’ mRNA levels resemble wildtype, suggesting post-translational defects. Class II mutations display immature core-glycosylation and shortened half-lives, indicating protein folding defects. Together, these experiments provide a comprehensive understanding of the disease-causing mutation’s defects in SLC13A5 Epilepsy at the biochemical and molecular level and shed light into the trafficking pathway(s) of NaCT. The two classes of mutations will require fundamentally different approaches for treatment to either restore transport function of the mutant protein that is capable of reaching the cell surface (Class I), or therapies that enable the correction of protein folding defects to enable escape to the cell surface where it may restore transport function (Class II).

Geodynamics of Super‐Earth GJ 486b

AbstractMany super‐Earths are on very short orbits around their host star and, therefore, more likely to be tidally locked. Because this locking can lead to a strong contrast between the dayside and nightside surface temperatures, these super‐Earths could exhibit mantle convection patterns and tectonics that could differ significantly from those observed in the present‐day solar system. The presence of an atmosphere, however, would allow transport of heat from the dayside toward the nightside and thereby reduce the surface temperature contrast between the two hemispheres. On rocky planets, atmospheric and geodynamic regimes are closely linked, which directly connects the question of atmospheric thickness to the potential interior dynamics of the planet. Here, we study the interior dynamics of super‐Earth GJ 486b ( , , K), which is one of the most suitable M‐dwarf super‐Earth candidates for retaining an atmosphere produced by degassing from the mantle and magma ocean. We investigate how the geodynamic regime of GJ 486b is influenced by different surface temperature contrasts by varying possible atmospheric circulation regimes. We also investigate how the strength of the lithosphere affects the convection pattern. We find that hemispheric tectonics, the surface expression of degree‐1 convection with downwellings forming on one hemisphere and upwelling material rising on the opposite hemisphere, is a consequence of the strong lithosphere rather than surface temperature contrast. Anchored hemispheric tectonics, where downwellings und upwellings have a preferred (day/night) hemisphere, is favored for strong temperature contrasts between the dayside and nightside and higher surface temperatures.

Genetic Signatures: CD44 Single-Nucleotide Polymorphisms Affect Cell Surface Expression and Elevate Risk in Head and Neck Squamous Cell Carcinoma.

This study aimed to investigate the impact of single-nucleotide polymorphisms (SNPs) in the CD44 gene, specifically in the 3'UTR region (rs13347) and intronic region (rs187115), on the cell surface expression of CD44 protein and the risk of development of head and neck squamous cell carcinoma (HNSCC). The study involved analysis of 85 samples and 85 healthy controls. Immunohistochemistry (IHC) and flow cytometry were used to assess cell surface protein expression using CD44 antibody. DNA from formalin-fixed paraffin-embedded tissue sections was isolated and amplified using targeted primers. Sanger sequencing of the resultant amplified products was performed to determine the genotypes of the CD44 rs13347 and rs187115 SNPs. GTEx and RegulomeDB were queried to evaluate the genotypic effects of these variants on target gene expression and regulation. A comparison between patients with HNSCC and healthy controls revealed a significant association between CD44 rs13347 and an increased risk of HNSCC in all the analyzed models, especially the TT genotype showed a significantly higher risk with an odds ratio of 8.69 (95% CI, 2.35 to 32.09; P = .0003). However, no significant association was found between CD44 rs187115 and HNSCC in any of the models analyzed (all P > .05). Other notable findings included significant associations between CD44 rs13347 genotype and age (P = .031), number of CD44-positive tumor cells (P = .049), CD44 staining intensity (SI; P = .039), and CD44 immunoreactivity score (IRS) status (P = .019). The T allele and homozygous TT genotype of CD44 rs13347 SNP were associated with increased susceptibility to HNSCC and decreased proportion of CD44-positive tumor cells, low SI, and reduced IRS.

Quercetin Attenuates MRGPRX2-Mediated Mast Cell Degranulation via the MyD88/IKK/NF-κB and PI3K/AKT/ Rac1/Cdc42 Pathway.

CMRF35-like molecule-1 (CLM-1) is a receptor of the CD300 family that inhibits MRGPRX2-mediated mast cell degranulation. Understanding the role and mechanism of CLM-1 agonist has significant implications for the treatment of allergic disease. Quercetin is a natural small molecule compound derived from plants and vegetables that has been shown to prevent histamine release by immune cells. This study aims to examine the inhibitory effects of quercetin on MRGPRX2-mediated mast cell degranulation via CLM-1. We found that C48/80 stimulation resulted in significantly increased release of β-hexosaminidase, histamine and Ca2+ in CLM-1-knockdown LAD2 cells than in NC-LAD2 cells. Surface plasmon resonance (SPR) and molecular docking analyses revealed high-affinity binding between quercetin and CLM-1 (K D = 2.962×10-5 mol/L) mediated by the formation of hydrogen bonds. In addition, quercetin can selectively bind to CLM-1 on mast cells, leading to SHP-1 phosphorylation and subsequent inhibition of downstream MyD88/IKK/NF-κB signaling. Furthermore, activation of CLM-1 modulated the surface expression of MRGPRX2 by inhibiting F-actin, leading to internalization of the MRGPRX2 receptor via the PI3K/AKT/ Rac1/Cdc42 pathway. Quercetin is a promising treatment for allergic diseases by acting as a CLM-1 agonist that inhibits MRGPRX2-mediated mast cell degranulation.

Revealing the Novel Role of Purinergic Receptor P2X4 in Phagocytic Uptake After Ischemic Stroke.

Purinergic receptor P2X4 (P2X4R), highly expressed on microglia and macrophages, is activated by ATP released from damaged cells and linked to poststroke inflammation. Previous studies showed that short-term P2X4R inhibition reduces inflammation and promotes long term recovery, but the mechanism underlying P2X4R and inflammation remains unclear. We hypothesized that P2X4R absence or pharmacological blockade can enhance macrophage phagocytic function by alleviating excessive inflammation after stroke. We divided P2X4R knockout and littermate control mice into 2 groups either naive or mice subjected to ischemic stroke surgery. Additionally, the regular WT mice subjected to ischemic stroke were treated with 5-(3-Bromophenyl)-1,3-dihydro-2H-Benzofuro[3,2-e]-1,4-diazepin-2-one BD (a P2X4R inhibitor) or vehicle. We isolated phagocytic cells from mice in each group and assayed phagocytic activity by quantifying uptake of fluorescent beads and bioparticles using flow cytometry or confocal microscopy and by measuring protein expression related to phagocytosis. Short-term inhibition of P2X4R with with 5-(3-Bromophenyl)-1,3-dihydro-2H-Benzofuro[3,2-e]-1,4-diazepin-2-one treatment upregulated ANXA1 (annexinA1). P2X4R absence prevented ATP-induced decline in phagocytic uptake in macrophages. Microglia or macrophages derived from P2X4R knockout mice showed significantly increased phagocytic activity compared with microglia/macrophages taken from littermate control mice. Cell surface expression of CD36, a scavenger receptor protein, increased after stroke, and was higher in P2X4R knockout mice. This study suggests that blockade or absence of P2X4R increases phagocytic uptake of damaged tissue following ischemic stroke. Taken together with previous reports detailing how P2X4R inhibition is protective following stroke, our results demonstrate P2X4R may mediate long-term resolution after ischemic stroke by enhancing phagocytic clearance.

Conjugate Riedel shears in a volcanic caldera: the case of the Laguna del Maule Volcanic Complex, Central Chile

The Andean intra-arc is characterized by large-scale continuous lineaments, often the direct surface expression of tectonic structures. In this study, we analyze the main lineaments around the Laguna del Maule Volcanic Complex, Central Chile (~36° S), to shed light on the main tectonic processes. We show that the lineament directions are consistent with structures based on a theoretical Riedel model and suggest the occurrence of two conjugate Riedel shears crossing Laguna del Maule. This structural arrangement can accommodate deformation related to either a transtensional regime, having a WNW-oriented master fault (Laguna Fea Fault), or a transpressional regime, characterized by NNE-oriented master faults (e.g., Melado Fault). In this context, the NE-striking Troncoso Fault would be a long-lived dextral fault compatible with both regimes. According to the Riedel model, ENE-oriented lineaments are predicted to be tensional structures, whilst NW-oriented structures (e.g., Los Cóndores Fault) would correspond to P-type structures accommodating compressional deformation. This tectonic architecture, characterized by the most intense deformation just at the intersection between shears, has likely promoted magma accumulation and would explain the compositional variability at Laguna del Maule. This study therefore demonstrates the usefulness of oriented lineament maps in interpreting regional tectonics for volcanically active areas.

Impaired excitability of fast-spiking neurons in a novel mouse model of KCNC1 epileptic encephalopathy.

The recurrent pathogenic variant KCNC1-p.Ala421Val (A421V) is a cause of developmental and epileptic encephalopathy characterized by moderate-to-severe developmental delay/intellectual disability, and infantile-onset treatment-resistant epilepsy with multiple seizure types including myoclonic seizures. Yet, the mechanistic basis of disease is unclear. KCNC1 encodes Kv3.1, a voltage-gated potassium channel subunit that is highly and selectively expressed in neurons capable of generating action potentials at high frequency, including parvalbumin-positive fast-spiking GABAergic inhibitory interneurons in cerebral cortex (PV-INs) known to be important for cognitive function and plasticity as well as control of network excitation to prevent seizures. In this study, we generate a novel transgenic mouse model with conditional expression of the Ala421Val pathogenic missense variant (Kcnc1-A421V/+ mice) to explore the physiological mechanisms of KCNC1 developmental and epileptic encephalopathy. Our results indicate that global heterozygous expression of the A421V variant leads to epilepsy and premature lethality. We observe decreased PV-IN cell surface expression of Kv3.1 via immunohistochemistry, decreased voltage-gated potassium current density in PV-INs using outside-out nucleated macropatch recordings in brain slice, and profound impairments in the intrinsic excitability of cerebral cortex PV-INs but not excitatory neurons in current-clamp electrophysiology. In vivo two-photon calcium imaging revealed hypersynchronous discharges correlated with brief paroxysmal movements, subsequently shown to be myoclonic seizures on electroencephalography. We found alterations in PV-IN-mediated inhibitory neurotransmission in young adult but not juvenile Kcnc1-A421V/+ mice relative to wild-type controls. Together, these results establish the impact of the recurrent Kv3.1-A421V variant on neuronal excitability and synaptic physiology across development to drive network dysfunction underlying KCNC1 epileptic encephalopathy.

Soluble MICA concentrations and genetic variability of MICA and its NKG2D receptor as factors affecting Graft-versus-Host Disease development after allogeneic haematopoietic stem cell transplantation

Despite new treatment strategies, graft-versus-host disease (GvHD) remains a formidable complication after allogeneic hematopoietic stem cell transplantation (HSCT). This study aimed to investigate the impact of polymorphisms and expression of MICA and NKG2D receptor on the development of GvHD in allogeneic HSCT recipients. Soluble MICA (sMICA) concentration was measured in serum collected 30 days after transplantation and the genetic variability of MICA and NKG2D genes was evaluated. The frequency of NKG2D+NK cells was determined by flow cytometry before and (21, 30, 60 and 90 days) after transplantation. Recipients with acute GvHD grades II-IV carried the NKG2D rs1049174 C allele more frequently than controls or patients with no or mild disease. Patients with chronic GvHD had higher frequency of NKG2D expressing NK cells posttransplant, reflecting increased activity of their NK cells. Although no direct relationship between MICA SNPs and GvHD were observed, the presence of MICA rs1051792 GG genotype correlated with elevated sMICA levels and increased serum level of sMICA was associated with higher risk of chronic GvHD. Our findings suggest that sMICA concentration may serve as a potential biomarker for chronic GvHD and emphasize the impact of genetic variability of NKG2D and its surface expression on the HSCT outcome.

Tubulin interaction at tubulin-binding sequence 1 (TBS1) is required for proper surface expression and TRPV1 channel activity

TRPV1, a polymodal and nonselective cation channel has unique gating mechanisms which is regulated by supramolecular complexes at the plasma membrane formed with membrane proteins, lipids and kinase pathways. Crosstalk between microtubule cytoskeleton with TRPV1 at various level has been established. Previously we demonstrated that the positively-charged residues present at specific tubulin-binding stretch sequences (i.e. TBS1 and TBS2, AA 710–730 and 770–797 respectively) located at the C-terminus of TRPV1 are crucial for tubulin interaction and such sequences have evolutionary origin. The nature of TRPV1-tubulin complex and its functional importance remain poorly understood. Here, we made several mutations in the TBS1 and TBS2 regions and characterized such mutants. Though these mutations reduce tubulin interaction drastically, a low and basal-level of tubulin interaction remains with these mutants. Substitution of positively-charged residues (Lys and Arg) to Ala in the TBS1, but not in TBS2 region results in reduced ligand-sensitivity. Such ligand-sensitivity is altered in response to Taxol or Nocodazole. We suggest that tubulin interaction at the TBS1 region favours channel opening while interaction in TBS2 favours channel closure. We demonstrate for the first time the functional significance of TRPV1-tubulin complex and endorse microtubule dynamics as a parameter that can alter TRPV1 channel functions. These findings can be relevant for several physiological functions and also in the context of chemotherapy-induced neuropathic pain caused by various microtubule stabilizing chemotherapeutic drugs. Thus, this characterization may indicate TRPV1 as a potential therapeutic target relevant for chemotherapeutic drug-induced peripheral neuropathies, neurodegeneration and other neurological disorders.